Me too, I didn't want to miss this mornings conjunction so I thought I may as well make the most of it and grab 930 while I still had my gear out. Though I'm paying for it now
That great image inspired me to drag out the canon and have a squiz, boy it sure is a big sucker even just looking through the filter itself and it is so close to the apparent center of the disk, the detail at high mag was also great from this location.
Didnt bother with a shot though, Paul's captures it very nicely
Rob, I only used the Baader solar film and a UV/IR filter. It didn't look too flash when I first did it, so I did did another run and stacked only the best 10 frames, sharpened them fairly severely and then applied and blended it as a artificial luminance layer to the original in photoshop.
Just a terrific image Paul! This leads me to a couple of questions (please forgive my ignorance, I'm new at this!) - what exactly is "positive eyepiece projection"? Do you project onto something, and what makes it "positive"? How do you get f40 - Barlows etc, or is it to do with the camera? I've mucked around lately with eyepiece projection to get images of the recent Mercury transit, sunspots etc, but just crudely with binoculars and a long cardboard box (telescope box!). Is your method in principle the same, just with much more sophisticated equipment?
Boy, that's a lotta questions!!! Sorry - if you ignore me I'll be suitably humbled!
There are basically 4 way to image through telescope, afocal (image 1), prime focus (2&3), positive projection (4&5) and negative projection (6&7). With my postive projection I use a variable projection adapter that allows me to vary the magnifying power.
Negative projection usually involves a barlow, powermate, teleconverter or some type of focal length multiplier. Positive projection involves using an eyepiece to project an image directly onto the recording surface (ccd, cmos or film).
For eyepiece projection there are formula you can use to work out effectivece focal length and f ratio etc. Attached is a zipped focal length calculator to help work these things out. You will need excel to use it. In the "Afocal Projection" worksheet fill out the details in the red squares for Telescope FL, eyepiece FLs, Camera lens FL and telescope aperture (Red boxes. Use numbers only no text, eg 50, not 50mm) All measurements are in millimeters.
Once you have done that if you check out the "EEP Positive Projection" sheet you will see the figures for FL, F/ratio, system magnification factor (Telescope FL/Eyepiece FL X magnification factor = final magnification)
Hope this helps
All images from Michael Covington's Astrophotography for the Amateur. Cambridge Press
Thanks so much for supplying such a detailed and informative response, Paul. Nothing beats a good diagram to explain the intricacies of these things, and I really appreciate your explanation and information.
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